The present invention relates to a multi-layered printed circuit board (PCB) for use in various items of electronic equipment, and more particularly to a multi-layered PCB whose shape can be adapted to the housing of electronic equipment whose shape has bent or convex-concave parts and a manufacturing method for such PCBs.
Some of the conventionally used items of electronic equipment, such as portable telephones and handy terminals, have housings whose prescribed parts are thicker elsewhere, convex or concave, or bent. However, flat multi-layered PCBs whose thickness and number of layers are fixed are used in such complexly shaped housings, resulting in the problem that the internal space of such housings has void parts which are not efficiently utilized. There arises another problem that bent and/or concave parts of the box prevent the multi-layered PCB from being thicker than a certain extent, and accordingly restricts the multi-layered wiring and inhibits sufficiently dense packaging of electronic parts.
As a solution to these problems, there is known a configuration in which a plurality of flat multi-layered PCBs are arranged to match the shape of the housing and these PCBs are connected by a flexible PCB. This configuration, however, is complex with an increased number of parts, and accordingly involves the problem of a greater number of manhours spent in its assembly and a correspondingly higher cost.
Meanwhile, examples of concave parts formed in multi-layered PCBs are disclosed in the Gazettes of the Japanese Patents Laid-open No. 62537 of 1991, No. 57653 of 1989 and No. 64187 of 1986. In all these examples, however, the concave parts for mounting electronic elements are machined, resulting in the problem of an increased number of manhours spent in (cost of) manufacturing. None of these examples of the prior art discloses a multi-layered PCB whose configuration is adaptable to the shape of the casing.